According to recent U.S. statistics, it is estimated that over 400,000 patients have a first-time stroke each year. In addition, stroke may be the leading cause of disability and the third leading cause of death. Men may be at a higher risk of having a stroke than women. About 80% of all strokes may be acute ischemic strokes (due to, e.g., intracranial thrombosis or extracranial embolism). About one quarter of all strokes occur in individuals under 65 years old, a figure which is somewhat at odds with a perception that stroke is a disease of the elderly.
An ischemic cascade may be initiated in the first seconds to minutes following the loss of perfusion to the brain. Absent therapeutic intervention, neurological damage results. This damage may be divided into two regions, an infarction area in which damage may be irreversible and an ischemic penumbra in which damage may be reversible. However, in the hours and days following loss of circulation, damage in the penumbra, like that in the infarct, becomes irreversible.